1 14 



STROBILOPSIDAE 



STROBILOPS AENEA Pilsbry 



A recently recognized species of Strobilops, aenea may be 

 known by its depressed spire and bluntly angular periphery. The 

 base of the shell is more flattened than that in any other species 

 of this genus. 



Strobilops aenea aenea Pilsbry. The shell of the typical 

 variety, which measures about one-eighth inch (2.00-2.75 mm.) 

 in diameter, is dark brown with a peculiar golden gleam, unlike 

 the coloration of any other shell of the genus. 



The typical Strobilops aenea has 2 emerging parietal lamellae, 

 the infraparietal being very thin and extending but a short 



distance beyond the edge of the peristome. Internally, the 

 parietal lamella is large and heavy, but the other lamellae are 

 thin, and the interparietal lamella is very short. The lamellae 

 are nodose or sawlike only far within the aperture. The 4 

 basal folds may be seen through the translucent base of the 

 shell. They are peculiar in the fact that they alternate in size. 

 The umbilicus is comparatively large. 



Like the typical Strobilops labyrinthica, the typical Strobilops 

 aenea is distributed widely in Illinois. The northernmost county 

 from which specimens of aenea aenea have been seen is La Salle, 

 and from this locality southward it is the most common Strobi- 

 lops. It has erroneously been recorded as labyrinthica, from 

 which it is markedly distinct. 



The usual habitat of Strobilops aenea aenea is in the higher 

 uplands, in forests of oak, elm, hickory, dogwood, walnut, sassa- 

 fras and ironwood. Only rarely is it found in a floodplain 

 valley and then only when the situation is dry. It is often 

 abundant under loose or started bark, on the underside of old 

 wood and on chips from forest cuttings. It occurs in old woods 

 and in recent cut-overs wherever logs and decaying wood have 

 accumulated. 



